Absorption refrigeration



EFRIGERATION 2 Sheets-Sheet l June 19, 1956 w. G. KOGEL ABSORPTIONREFRIGERATION Original Filed July 14, 1949 2 Sheets-Sheet 2 StatesABSORPTIN REFRIGRATION Wilhelm Georg Kegel, Stockholm, Sweden,assignox;V to

Aktiebolaget Elektroiux, Stockholm, Sweden, a corporation of SwedenClaims priority, application Sweden July 22, 1948 21 Claims. (Cl.62-119.5)

This invention relates to refrigeration and is especially concerned withrefrigeration systems of the absorption type and refrigerators embodyingsuch systems or apparatus. This application is a division of myapplication Serial No, 104,771, led luly 14, 1949, now Patent No.2,655,010, granted October 13, 1953.

The objects of this invention are to provide an improved refrigerationsystem of this type having a new arrangement and relationship of partsor members which not only contribute to a compact apparatus or unit butalso provide for efficient heat exchange between lluids circulating inthe system and insure reliable operation undervall operating conditionsencountered in practice; to provide in such a system an arrangement inwhich one component or member forms a unitary or integral part of one orseveral other members; to combine several components or members in oneunitary or integral part whereby etiicient heat exchange may be effectedbetween fluids circulating in the system; to provide such a unitary orintegral part in the circuit for circulation of refrigerant which servesas a pressure vessel for inert gas and is in good thermal relation withthe inert gas circuit to promote use of such vessel as an extension ofthe condenser; to provide such a pressure vessel which is advantageouslyutilized to conduct refrigerant therefrom to an evaporator; to provide anew relationship of parts in the circuit for absorption liquid in whicheicient heat exchange between iiuids in such circuit is promoted and atthe same time loss of heat from such uids to the surroundings isminimized; to provide an improvement for varying the quantity ofrefrigerant Huid actively circulating in the system; to provide animproved arrangement for raising liquid refrigerant from a condenser toa higher level, as to the evaporator, for example, whereby reliablelifting or pumping of such refrigerant is always assured; and to providea unitary and compact condenser and absorber construction wherebyeliicient air cooling of such parts by natural draft circulation iseffected. l

The novel features which are believed to be characteristic of theinvention are set forth with particularity in the claims. The invention,both as to organization and method, together with the above and otherobjects and advantages thereof, will be better understood by referenceto the following description taken in conjunction with the accompanyingdrawings forming a part of this specification, and of which:

Fig. 1 illustrates more or less diagrammatically an absorptionrefrigeration system of the inert gas type embodying the invention;

Figs. 2 to 5 are fragmentary views diagrammatically illustratingmodifications of the system shown in Fig. l;

and

Fig. 6 is an elevation view of a refrigeration system like that shown inFig. l diagrammatically illustrating another embodiment of theinvention, the system being fixed to framework adapted to be mounted ina refrigerator cabinet.

arent O A 2,750,763 Patented .lune 19, 1956 ICC In Fig. l the inventionis shown embodied in an abso'rption refrigeration system of a typeemploying an inert gas or pressure equalizing agent. Systems of thistype are well known and include a generator or vapor expulsion riit 1li,a condenser 11, an evaporator 12 and absorber 14 which are connected toone another to provide circuits for circulation of refrigerant fluid,inert gas and absorption liquid. By way of example, ammonia may beemployed as the refrigerant, hydrogen as the inert 'gas and water as theliquid absorbent.

The vapor expulsion unit 1t), which is enveloped within a body 9 ofsuitable insulating material, may comprise a boiler 15 in the form ofpiping to which heat is supplied from a heating tube or flue 16thermally connected therewith at 17, as by welding, for example. Theheating tube 16 may be heated in any suitable manner, as by anelectrical heating element disposed within the lower part of the tube 16o r by a liquid or gaseous fuel burner which is adapted to project itsflame into the lower end of the tube.

Flfhe `heat supplied to the boiler 15 and its contents expelsrefrigerant vapor out of solution, and the refrigerant vapor passesthrough a rectifier 18 into the air cooled condenser 11 in which it iscondensed and liquefied. In a manner to be described hereinafter, liquidrefrigerant is conducted from condenser 11 to evaporator 12 in a path offlow which includes conduits 19 and 20, the evaporator beingdiagrammatically shown and arranged to effect cooling of athermallyinsulated space 21. In evaporator 12 liquid refrigerant evaporates anddiffuses into an inert pressure equalizing gas, such as hydrogen, whichenters through a conduit 22. Due to evaporation of refrigerant fluidinto inert gas in evaporator 12, a refrigerating effect is produced withconsequent absorption of heat from the surroundings.

The rich gas mixture of refrigerant vapor and inert gas formed inevaporator 12 flows from the lower part thereof through one passage 23of a gas heat exchanger 24 and conduits 2S and 26 into the lower end ofthe absorber 14 which is in the form of a looped coil. In the absorber14 the rich gas mixture flows countercurrent to downwardly owingabsorption liquid which enters through a conduit 27. The absorptionliquid absorbs refrigerant vapor from inert gas, and inert gas weak inrefrigerant ilows from the upper end of absorber 14 through a conduit2S, another passage 29 of gas heat exchanger 24 and conduit 22 into theupper part of evaporator 12. In Fig. 1 the evaporator 12 is connected inthe inert gas circuit just described in such manner that parallel flowof inert gas and refrigerant uid is effected in the evaporator. However,it should be understood that the evaporator 12 may be connected in thegas circuit in any other desired manner so that, for example, inert gas'and refrigerant iiuid pass in counterow with respect to one another.

The circulation of gas in the gas circuit just described is due to thedifference in speciiic weight of the columns of gas rich and weak,respectively, in refrigerant vapor. Since the column of gas rich inrefrigerant vapor and owing from evaporator 12 to absorber 14 is heavierthan the column of gas weak in refrigerant and flowing from absorber 14to evaporator 12, a force is produced or developed within the system forcausing circulation of inert gas in the manner just described. y

In a manner to be described hereinafter, absorption solution enriched inrefrigerant flows from the lower part of the absorber 14 through aconduit 30 into the upper part of boiler 15. From the lower closed endof boiler 1-5 absorption solution passes into the lower end of avertically extending tube 31 in which liquid is raised by vapor-liftaction, the tube 31 being heat conductively connected to the heatingtube 16, as by welding, to effect such lifting of liquid. The raisedliquid passes from the upper end of tube 31 into the upper part of astandpipe or riser 32, and, as will be described presently, absorptionliquid weak in refrigerant flows from the lower part thereof to theabsorber 14 in a path of fiow which includes conduit 27.

The standpipe or riser 32 may or may not be heat conductively connectedto the heating tube 16. The principal part of generated vapor producedin the vapor expulsion unit is expelled from solution in boiler 15, andliquid of decreasing refrigerant concentration flows downwardly towardthe bottom end thereof into the vapor-lift tube 31. A liquid column ismaintained in the standpipe 32 whose liquid surface is at such a levelthat absorption liquid weak in refrigerant can ow by gravity from thelower end of the standpipe into the upper part of the absorber throughthe conduit 27.

The vapor passing from the upper end of vapor lift tube 31 into thevapor space of standpipe 32 ows therefrom through a downwardly extendingconduit 33 into the lower end of a horizontally extending pipe section15a formed at the upper part of boiler 15. The pipe section 15aconstitutes an analyzer into which passes vapor generated in the boiler15 and in the vapor lift tube 31. The generated vapor usually is amixture of refrigerant vapor and absorption liquid vapor. When ammoniais employed as the refrigerant and water as the absorbent, for example,the generated vapor usually is a mixture of ammonia vapor and watervapor. Due to the difference in boiling points of ammonia and water,water vapor may be removed from ammonia vapor by cooling the mixture tocondense out the water.

In Fig. l vapor generated in the boiler pipe 15 passes upwardlytherefrom through the pipe section 15a, and vapor generated in tube 31also enters such pipe section through conduit 33. The absorption liquidintroduced into the pipe section or analyzer 15a is relatively rich inrefrigerant and at a lower temperature than the generated vapor, and inbubbling through the enriched absorption solution at least a part of thewater vapor is cooled sufficiently and condenses, thus removing watervapor from ammonia vapor. rIhe latent heat of condensation resultingfrom condensation of water vapor is given up to the enriched absorptionsolution and forms an internally heated zone in which some ammonia vaporis expelled out of solution. Such refrigerant vapor mixes withrefrigerant vapor generated in the vapor lift tube 31 and boiler 15, andthe mixture passes from the analyzer 15a to the rectifier 18.v

In the rectifier 18, which may be provided with internal baies 34,further cooling of generated vapor is effected which is sufficient tocause condensation of water vapor and thereby effect its removal fromammonia vapor. Such condensate drains downwardly in the rectifier 18 andmixes with enriched absorption solution flowing to the boiler 15. Thelatent heat of condensation resulting from rectification of generatedvapor, that is, condensation of water vapor, is usually referred to asheat of rectification.

In accordance with this invention liquid refrigerant formed in condenser11 is raised therefrom to a higher level in such manner that positiveraising or lifting of refrigerant liquid is assured under all operatingconditions encountered, particularly when the system is placed inoperation following a shut down period. In the embodiment of Fig. 1 thisis accomplished by providing a conduit or vessel 3S to an intermediateportion of which the outlet end 36 of the condenser 11 is connected.

Liquid refrigerant formed in condenser 11 flows therefrom into vesseland accumulates in the lower part thereof. From vessel 35 liquidrefrigerant flows through conduit 19 into the lower part of verticallyextending conduit 20 which is heat conductively connected with therectifier 18 at 37, as by welding, for example. Due to heat ofrectification supplied from the rectier 18, liquid refrigerant is raisedby vapor lift action through conduit 20 to an air cooled condenser 38which may be provided with a plurality of heat dissipating members 39.

The vapor formed in the lower part of conduit 2t) for raising liquidtherethrough passes from the upper end of such conduit into condenser 38and is condensed and liquefied therein. The raised liquid refrigerantand refrigerant condensed in condenser 38 flows through a conduit 40into the upper part of evaporator 12 for gravity flow through thelatter, as previously explained.

If desired, the condenser 38 may be omitted and an arrangement providedin which the lifting vapor passing from the upper end of conduit 20 isreturned to the vessel 35 which essentially serves as an extension ofcondenser 11 and in which returned vapor is condensed. Such amodification is shown in Fig. 2 in which the upper end of conduit 20 isconnected to the upper part of the vertical leg 41 of a generallyU-shaped liquid trap 42 whose horizontally extending leg 43 is connectedat the outer end thereof by a conduit 44 to the upper end of evaporator12. When liquid refrigerant in liquid trap 42 reaches the level at whichconduit 44 is connected thereto, liquid refrigerant overflows throughsuch conduit into evaporator 12 for gravity fiow through the latter. Theconduit 2t? is connected to leg 41 at a level above the connection ofconduit 44 to leg 43, that is, the vapor space of leg 41, and liftingvapor passes from such vapor space through a conduit 45 to the vessel 35in which the vapor is condensed and liquefied.

The heat conductive connection 37 between conduit 20 and rectifier 18extends for a sufficient distance lengthwise of these members to insuresuch transfer of heat of rectification to conduit 20 that vaporizationof liquid refrigerant will occur in the latter to insure lifting ofrefrigerant by vapor lift action. The conduit or lift tube 20 is thusheated to a definite temperature, depending upon the boiling point ofsubstantially pure refrigerant under conditions prevailing in thesystem, to cause vaporization of such refrigerant or refrigerant havinga relatively small concentration of liquid absorbent. The diameter ofconduit 2() is sufficiently small so that the vapor bubbles formed dueto heat transfer in this manner cannot freely pass liquid in conduit 20,thereby effecting lifting of liquid by vapor lift action. Such liftingof liquid is accomplished under the influence of the column of liquid invessel 35 whose liquid surface level may be at the level indicated at 46in Fig. l, for example, such liquid column usually being referred to asa reaction head which overbalances the column of vapor bubbles andliquid slugs therebetween being raised in conduit 20.

Vaporization of liquid refrigerant in conduit 2f) by heat ofrectification takes place at a relatively low temperature. When theconcentration of or quantity of absorption liquid present in liquidcooling agent or refrigerant in conduit 20 becomes too high,vaporization of such liquid by heat of rectification often cannot takeplace at such relatively low temperature because the presence of liquidabsorbent increases the boiling temperature, that is, the temperature atwhich vaporization occurs. This is especially true when the conduit orvessel 35 contains liquid which is essentially liquid absorbent andwhich may occur, for example, when the system is turned or canted duringtransportation or being moved from one place to another.

In order to insure positive and reliable raising or lifting vof liquidrefrigerant under the most adverse operating conditions encountered,particularly when the refrigeration system is being started, provisionis made for removing liquid absorbent from the liquid lifting systemformed by vessel 35 and conduits 19 and 2t). In the embodiment of Fig. lthis is accomplished by providing a conduit 47 whose lower endcommunicates with the conduit 19 and lower end of conduit 20 and whoseupper end is preferably connected to rectifier 18 at a level which issubstantially at or slightly above the liquid surface level of theensures liquid column maintained in vessel 35 during operation of thesystem, such liquid column constituting the reaction head for pumping orraising xiquid refrigerant, as previously explained.

lf it is assumed the liquid lifting system contains liquid which isessentially or for the most part liquid absorbent when the refrigerationsystem is started following a shut down period, the vessel 35 willcontain such liquid absorbent. Under these conditions liquid refrigeranthaving a relatively small concentration of liquid absorbent will beformed in condenser ll and flow therefrom into vessel 35 and graduallysettle over the body of liquid absorbent. In this way liquid absorbentin vessel l35 will be displaced from the latter and pass throughconduits 19 and 47 into the rectifier 18. Eventually all of the liquidabsorbent in vessel 35 and conduit 19, as well as the liquid absorbentin conduit 2d, will be replaced by liquid refrigerant having arelatively small concentration of liquid absorbent, thereby enablingconduit to function and cause lifting of liquid refrigerant therethroughby vapor lift action by heat of rectification, as previously explained.The liquid absorbent entering rectifier 1S from the upper end of conduit47 flows downwardly by gravity and finds its way to the absorptionliquid circuit.

In view of the foregoing, it will now be understood that positive andreliable lifting or pumping or liquid refrigerant from condenser 11 to ahigher level can always be effected, even under the most adverseoperating conditions encountered, by removing liquid absorbent from theliquid lift or pump system. In Fig. 3 is illustrated another manner ofremoving liquid absorbent from the liquid lifting system which isespecially effective in promoting rapid lifting of liquid refrigerantfrom condenser 11 to a higher level. The embodiment of Fig. 3 differsfrom that of Fig. 1 in that conduit 47 is replaced by a conduit 48 whichis more or less U-'shaped to form a liquid trap having one leg 49communicating with the conduit 20 at approximately the liquid level 46in vessel 35 and the other leg 50 communicating with the rectifier 18 atthe same level or possibly slightly higher level.

The connections of conduit 43 to the conduit 20 and rectifier 18 may beaccomplished by forming small openings 51 and 52 in the latter, andsecuring the upper open ends of legs 49 and 50 to the conduit 20 andrectifier 18, respectively, at regions surrounding such openings. Inaddition, conduit 48 is formed of relatively small or narrow tubing todevelop a definite resistance to passage of liquid even before theU-shaped trap formed by this conduit is completely filled with liquid.In the event the liquid lifting system of Fig. 3 contains liquidabsorbent, such absorbent is replaced by liquid refrigerant having arelatively small concentration of absorbent substantially in the samemanner as in the embodiment of Fig. l and described above. However, inFig. 3 liquid absorbent is displaced from vessel and forced throughconduit 19 and lower part of lift tube or conduit 20 into the U.,shapedconduit 48. From conduit 48 such liquid absorbent passes into rectifier1S, and ultimately conduit 20 will contain liquid refrigerant having arelatively small concentration of absorbent, so that lift tube 20 willeffectively function to raise such liquid therethrough.

In accord with the invention the embodiment of Fig. l embodiesprovisions for varying the quantity of refrigerant fluid circulating inthe refrigeration system for producing useful refrigeration. This isaccomplished by providing a vessel 53 in which refrigerant fluid is heldin an inactive portion of the refrigeration system under certainoperating conditions. The vessel 53, which may be referred to as aconcentration vessel, is connected toreceive liquid refrigerant in thelower part thereof through a conduit S4 whose upper end is connected at55 to the conduit 25 immediately ahead of a barrier or darn 56 withrespect to the direction of flow of liquid from the Vevaporator 12.

In this manner unevaporated liquid refrigerant passing from the lowerend of evaporator 12 and flowing through the inner passage 23 of gasheat exchanger 24 is diverted by the dam or barrier S6 into conduit 54through which it is conducted to vessel 53 and collects therein. Thevessel 53 is heat conductively connected to rectifier 18 in any suitablemanner, as by welding, so that heat of rectification is transferred byrectifier 18 to vessel 53 and its contents. Vaporization of liquidrefrigerant continuously takes place in vessel 53 due to such heating,and such vapor passes upwardly from the vessel through a connection S7into the extreme upper part of rectifier 18 and flows into the condenser11 along with vapor flowing from the rectifier into the condenser.

When the load on evaporator 12 increases less unevaporated refrigerantpasses from the lower end thereof; and, when the evaporator loadincreases sufficiently, all of the refrigerant supplied to theevaporator 12 evaporates and. diffuses into inert gas therein to produceuseful refrigeration. Under such operating conditions the ow of liquidrefrigerant to vessel 53 through conduit 54 ceases; and, with continuedevaporation of liquid refrigerant in vessel 53 by heat transfer theretofrom rectifier 18, refrigerant vapor flows therefrom to condenser 11until the vessel is depleted of liquid.

Hence, when the load on evaporator 12 increases, as when ice trayscontaining water to be frozen are positioned in an ice freezingcompartment of the thermally insulated space 21, for example, a greaterquantity of refrigerant iiuid actively circulates in the refrigerationsystem to promote useful refrigeration and take care of increase inload. Conversely, when the load on the evaporator 12 decreases andunevaporated refrigerant passes from the lower end thereof, suchrefrigerant fluid collects in vessel 53 when it flows thereto at afaster rate than that at which it evaporates due to heating from therectifier 18. While unevaporated refrigerant may be allowed to drainthrough a liquid trap in conduit 54 directly into the bottom part ofvessel 35 and mix with refrigerant therein, it will be understood fromthe foregoing that certain advantages are realized by providing theconcentration vessel 53 which functions in the manner just described.

The vessel S3 is connected in the system in such manner that removal ofliquid therefrom, even a mixture of liquid refrigerant and absorbent, isreadily effected without any additional provisio-ns. Liquid absorbentpresent in vessel 53 is vaporized therein and the vapor thus formed,which is not required to lift liquid by vapor lift action, passes intocondenser 11 from which it is drained into the absorption liquidcircuit, as previously described. Also, the refrigeration system may besuch that there is inadequate space in the system for storing andholding a large quantity of excess refrigerant. By providing the vessel53, such excess refrigerant is effectively withheld from circulation andreturned to the active portion of the system to produce usefulrefrigeration Without the necessity of draining such refrigerant intothe absorption liquid circuit.

In absorption refrigeration systems of the inert gas type beingdescribed, it is usually the practice to provide a separate vessel whichis connected to the outlet end of the condenser and to the gas circuit,respectively, so that any inert gas which may pass through the condensercan flow into the gas circuit. Refrigerant vapor not liquefied in thecondenser flows into such separate vessel to displace inert gastherefrom and force such gas into the gas circuit. The effect of forcinggas into the gas circuit in this manner is to raise the total pressurein the entire system whereby an adequate condensing pressure is obtainedto insure condensation of refrigerant vapor in the condenser. For thisreason the separate vessel connected in the refrigeration system in themanner just described is usually referred to as a pressure vessel.

In further accord with the invention, in order to simplify therefrigeration systemand provide a compact arrangement of components orparts, the vessel or conduit 35 is arranged to serve as a pressurevessel which surrounds or envelops the conduit 26 and forms a jacketabout the latter. The outlet end of condenser il. is connected to anintermediate part of pressure vessel 35, so that the lower part thereofserves as a place for holding liquid refrigerant flowing thereto fromthe condenser. Further, the upper part of conduit 26 is formed with anopening 58 to connect the pressure vessel 35 to a part of the gascircuit so that the latter will function in the manner described above.Therefore, as illustrated in Fig. l and just described, the vessel 35serving as the pressure vessel of the refrigeration system forms aunitary or integral part of at least one other member or component ofthe system. In the embodiment of Fig. l the vessel 35 and the manner inwhich it envelops conduit 2d actually makes the pressure vessel anintegral part of several members of the refrigeration system andeliminates connections previously necessary, especially the conduitconnections to such a pressure vessel when a separate vessel is employedfor such purpose.

By employing vessel 35 as a pressure vessel which envelops conduit 26,desirable heat exchange between fluids in the system is effected,particularly to effect cooling and Condensation of refrigerant in vessel35 which passes therein from condenser 11. Since gas enriched inrefrigerant, which is relatively cold, flows through conduit 26, it isdesirable to shield the latter thermally from atmospheric air to avoidcondensation of moisture at the outer surfaces thereof. In Fig. l thisis effectively accomplished by employing vessel 35 as a jacket aboutconduit 26. In order to shield all parts of the path of flow forrelatively cool enriched gas, the conduit 25 and adjacent ends of gasheat exchanger 24 and vessel 35 may be enveloped in a body 58b ofsuitable insulating material, as shown in Fig. 4, Alternatively, the gasheat exchanger 24 and vessel 35 may be so .formed and connected in therefrigeration system that adjacent ends of these members or componentsare in abutting relation at 59, as shown in Fig. 5, thereby completelyenveloping conduit 26 for the relatively cool rich gas. In thearrangement of Fig. 5, the conduit 28 through which gas weak inrefrigerant flows from absorber 14 desirably is shifted to the outerextreme end ofthe gas heat exchanger 24.

It is usually the practice to mount the refrigeration system orapparatus on a wall of a household refrigerator cabinet, particularlythe rear wall of such a cabinet, for example. In such case the lateralside walls of the outer shell of the cabinet project rearwardly from therear insulated wall to form a vertically extending space for housingparts of the refrigeration apparatus. Such vertically extending spacemay be completely open or closed or partly closed by a wall member. lnany event the vertically extending space, due to the positioning of heatdissipating parts of the refrigeration apparatus therein, promotesupward natural draft circulation of air for cooling such heatdissipating parts which include the condenser, absorber and pressurevessel.

The embodiment of Fig. l lends itself to efficient air cooling becausethe absorber 14, condenser il and pressure vessel 3S provide a compactunitary construction in which the pressure vessel is contacted byupwardly flowing cooling air at substantially the same time such coolingair sweeps over the surfaces of the condenser. Further, the straightportion of the piping forming the condenser` 11 may form an elongatedcoil which encircles and is more or less wrapped about the pressurevessel 35, thereby tending to localize the regions at which heat isgiven up to cooling air and making more effective the induced naturaldraft circulation of air over these parts. Since the pressure vessel 35is effectively cooled, it serves as an extension of the condenser ll. inwhich effective condensation of refrigerant vapor takes place, therebycontributing to a compact condenser and pressure vessel construction. Itis for this reason that the condenser 38 of Fig. l may be omitted, ifdesired, and t'ne arrangement of Fig. 2 employed in which vapor forlifting liquid can be returned from the upper end of lift tube orconduit 8 20 to the pressure vessel 35, as shown in Fig. 2 and describedabove.

As stated above, the condenser may envelop the presl sure vessel 35 inwhich case the straight sections of the condenser 11 are disposed inspaced apart vertical planes. Similarly, the absorber coil 14 may beformed in a similar manner, and, by virtue of the compact arrangement ofthese parts, they can be treated or considered as a single component inthe fabrication of the refrigeration apparatus. This is especiallyimportant when heat dissipating members are provided on the absorbercoil 14 which also may be utilized as heat transfer members for thecondenser 11. Such a construction is shown in Fig. 1 in which the lengthof the tins 60 is approximately the same as the overall height of thecondenser l1 and absorber 14. It is to be understood that a separategroup of such fins 60 may be provided for the straight sections of thecondenser 11 and absorber 14 in each vertical plane of such straightsections, thereby providing a vertically extending air shafttherebetween in which the pressure vessel 35 is disposed and subjectedto vigorous cooling eifect by the natural draft circulation of airinduced in the manner described above.

This arrangement of condenser 11, absorber 14 and pressure vessel 35 isespecially important in a refrigeration system of the type shown in Fig.l in which the condenser is located below the evaporator. This is sobecause the compact condenser, absorber and pressure vessel structure islocated at a relatively low level compared to the overall height of theapparatus. With such construction heat is dissipated from all of theheat emitting parts or components near the lower part of the apparatusspace which tends to promote a driving upward force to cooling air beingcirculated by natural draft circulation. Such driving upward forceimparted to cooling air can be accentuated by closing off the open sideof the vertically extending apparatus space previously described fromthe upper end of the cabinet down to the condenser or, if desired, to apoint immediately below the absorber. In this way a good chimney effectcan be provided to cause upward movement of air by natural draftcirculation over the heat emitting parts of the apparatus to take upheat dissipated therefrom.

In another phase of the invention special consideration is given to thestoring of enriched absorption liquid in the absorption liquid circuit.It is usually the practice to ow enriched absorption liquid from theabsorber coil to a vessel and collect liquid therein, such collectedliquid forming the upper part of a liquid column under the inuence ofwhich liquid is raised to a higher level in the vapor expulsion unit.Since heat of absorption is liberated in the absorber coil, suchenriched absorption liquid collecting in the storage vessel isrelatively warm. It is customary to flow such warm absorption liquid inthermal relation with weak absorption liquid passing from the vaporexpulsion unit to the absorber coil in a liquid heat exchanger whichconstitutes a separate part or component of the refrigeration apparatus.

In further accord with the invention a vessel 61, which is connected toreceive enriched absorption liquid from the absorber 14 through conduit30, is enveloped in the same body 9 of insulation enveloping the vaporexpulsion unit 10 and constructed and connected in the refrigerationsystem so that the warm enriched liquid is advantageously utilized toeffect heat transfer with weak absorption liquid and generated vapor oreither of these fluids.

As seen in Fig. 1, the vessel 61 for storing enriched absorption liquidis enveloped in the single body 9 of insulating material and suchenriched absorbent rises upwardly therein from the connection of conduit30 to the upper part thereof within which the horizontally extendingpipe section or analyzer 15a projects. Below the pipe section 15a ispositioned a vertically extending coil 62 whose upper end is connectedto receive Weak absorption enseres liquid from the lower part ofstandpipe 32 through a conduit 63. Hence, weak absorption liquid isconducted downwardly through coil 62 and heat transfer is effectedbetween such weak liquid and rich absorption liquid rising in vessel 61.In addition, conduits 27 and 31 may be arranged in heat exchangerelation at 64, as by welding, so that further counteriiow heat exchangecan be effected between these fluids.

By way of example and without limitation, the vessel 61 may be of suchsize that it can hold from- ().75 to 2 liters of absorption solutionwhich may constitute 60 per cent or more of the entire quantity ofliquid absorbent held in the refrigeration system. ln other words, theupright vessel 61 in the immediate vicinity of the generator is arrangedto hold a major portion of the absorption solution circulating in thesystem. Since the enriched liquid absorbent passing from absorber 14 isrelatively warm, it will be understood that an arrangement has beenprovided whereby heat is effectively conserved within the system, theliquid in the insulated liquid body within vessel 61 being in efficientheat transfer relation with weak liquid absorbent in coil 62. Further,by projecting the analyzer 15a into the upper part of vessel 61 belowthe liquid level therein, a compact arrangement is also provided toeffect heat transfer between enriched absorption liquid and generatedvapor in the manner previously described.

In Fig. 6 is shown a refrigeration system generally like thatillustrated in Fig. 1 in which similar parts are designated by the samereference numerals. The vapor expulsion unit 10a of Fig. 6 is envelopedin a body 9a of suitable insulation and comprises a boiler 15b in theform of a Vertical p-ipe having an upper extension which constitutes therectifier 18a having baffles 34a therein. Heat is supplied to boiler 15bfrom a heating tube 16a thermally connected therewith at 17a, suchheating tube being of a type adapted to be heated by an electricalheating element therein. However, the heating tube may be arranged toextend entirely through the insulation body 9a and adapted to be heatedby a gaseous or liquid fuel burner at the lower end thereof.

As will be described presently, enriched absorption liquid flows fromabsorber 14a in a path of flow which includes a conduit 65 and an innerpassage of liquid heat exchanger 66 whose upper end is connected at 67to boiler 15b at a region below the liquid surface level maintained inthe latter. To the lower end of boiler 15b is connected the lower end ofvapor lift tube 31a thermally connected at 68 to the heating tube 16a.Liquid of decreasing `refrigerant concentration flows downwardly inboiler 15b, and liquid is raised by vapor lift action in tube 31a to theupper part of standpipe or riser 32a. Absorption liquid weak inrefrigerant passes from the lower end of standpipe 32a into the outerpassage of liquid heat exchanger 66 and thence through conduit 27a intothe upper part of absorber 14a.

Vapor for lifting absorption liquid through lift tube 31a passes fromthe upper end of standpipe 32a through a conduit 33a into the upperinclined section 15e of boiler 15b and bubbles through liquid therein,such inclined section constituting an analyzer similar to the analyzer15a in Fig. 1'. The vapor generated in boiler 15b andv lifting vaporentering through conduit 31a passes from analyzer 15C into rectifier 18aand into condenser 11a in which refrigerant vapor is condensed andliquefied.

The lower end of condenser 11a is connected at 68a to vessel 35a whichis disposed about conduit 26a through which relatively cool enriched gasfiows from evaporator 12a to absorber 14a. Liquid refrigerant flows fromvessel 35athrough conduits 19a and 20a and is raised in the latter to acondenser 38a provided with cooling fins 39a. The lifting vapor iscondensed in condenser 38a and such` condensate, together with raisedliquid, is conducted to the evaporator 12a in the same manner thatliquid is conducted from condenser 38 to evaporator 12 in Fig. 1.

Evaporator 12a isconnected in a gas circuitwhich. includes a gas heatexchanger 24a, only the outer end of'which, is seen in Fig. 6-. In orderto simplify Fig. 6, the' connections between evaporator 12a and gas heatexchanger 24a are not shown, it being understood that such connectionsare similar to those illustrated in Fig. 1 and described above.

The vessel 35a in Fig. 6 differs from theV corresponding vessel 35 inFig. 1 in that it is divided by a partition 69- to form an upper space70 and a lower space 71. The part of vessel 35a serving as` the pressurevessel forms a jacket about conduit 26a, the lower end of whichterminatesv at an opening in partition 69. The lower space 71constitutes the absorber vessel of the refrigeration system toanintermediate region of which the absorber coil 14a is connected at 72.

The operation of the system shown in Fig.. 6 is generally like thatdescribed above in connection with Fig. l.y In Fig. 6 gas enriched inrefrigerant ows from evaporator 12a through the inner passage of gasheat exchanger 24a and conduits 25a and 26a into the space 71' of vessel35a. From the upper part of such` space 71 the enriched gas fiowsupwardly through absorber coil 14a countercurrent to weak absorptionliquid which enters the upper part of absorber 14a through conduit 27a.lnert gas weak in refrigerant flows from the upper part of absorber 14athrough conduit 28a and outer passage of gas heat exchanger 24a to theevaporator 12a. As previously stated, liquid refrigerant is supplied tothe evaporator from condenser 38a through conduit 40a.

Liquid refrigerant formed in condenser 11a flows therefrom into theupper space 7u of vessel 35a and collects in the bottom part thereof. Asin the embodiment of Fig. l, the space 7i) communicates with the gascircuit through an opening 58a formed in conduit 26a. One end of conduit19a is connected at 73 to vessel 35a to withdraw liquid refrigerant fromthe bottom of space 79. From conduit 19a liquid refrigerant passes intoconduit or lift tube 20ct which is heat conductively connected at 37a torectifier 18a. A conduit 47a similar to conduit 47 in Fig. l is providedfor removing liquid absorbent from space '71) and conduits 19a and 20a.Such conduit 47a at its upper end is connected to rectifier 13a forconducting liquid absorbent to the latter which then ows by gravity inthe rectifier into the absorption liquid circuit.

The conduits 1.911,2@ and 47a in Fig. 6 correspond to the conduits 19,2t) and 47 in Fig. l and the part of the description of Fig. l directedto the function and opera` tion of these members is equally applicableto the corresponding members in Fig. 6. Although not shown, it is beunderstood that Fig. 6 may also embody a concentration vessel like thevessel 53 in Fig. l and conduit connections S4 and S7 associatedtherewith.

From the absorber 14a enriched absorption liquid flows into the lowerspace 71 of vessel 35a which constitutes` the absorber vessel. From thisvessel enriched liquid flows through conduit 65 to the boiler 15b aspreviously explained.

ln Fig. 6 the condenser 11a and absorber 14a may be formed of iiattenedlooped piping each having straight sections in spaced apart verticalplanes, and separate groups of cooling fins 60a may be provided for thestraight coil sections in each vertical plane, each fin being utilizedboth for the condenser and absorber. In this manner an air shaft isformed between the spaced apart straight coil sections within which thevessel 35a isl disposed. Hence, the advantages described above inconnection with Fig. l concerning the compact arrangement and cooling ofvessel 3S, condenser 11 and absorber 14 are equally applicable to thesimilar compact arrangement of vessel 35h condenser 11a and absorber 14aof Fig. 6. it should be further understood that the modifiedconstructions iliustrated in Figs. 2 to 5 in connection with theembodiment of Fig. l are also equally applicable to the embodiment ofFig. 6.

In Fig. 6 the refrigeration apparatus is fixed at a number of places 74,as by welding, to a frame 75 formed of angle members 76, 77, 78 and 79.Such frame 7S may be removably secured to a household refrigeratorcabinet at the rear insulated wall thereof so as to position theapparatus in a vertically extending space defined by the rear insulatedwall and rearwardly extending parts of the lateral side walls of theouter metal shell of the cabinet. When the frame 75 and apparatus fixedthereto are mounted in position, the evaporator 12a is adapted to bepositioned within the thermally insulated interior of 'the cabinetthrough an opening in the rear insulated wall which may be closed by aninsulated closure niember, Hence, the advantages described above, inconnection with the embodiment in Fig. l when such system is mounted ina vertically extending apparatus space like that just described, arealso realized in the embodiment of Fig. 6.

Modifications of the embodiments of the invention which have beendescribed and illustrated will occur to those skilled in the art, sothat it is desired not to be limited to the particular arrangements setforth. Moreover, certain features of the invention can be advantageouslyemployed independently of other features. Therefore, it is intended inthe claims to cover all those modifications and features which do notdepart from the spirit and scope of the invention.

What is claimed is:

l. In the art of refrigeration with the aid of an absorptionrefrigeration system having a circuit in which inert gas normallycirculates in a path of flow including a place of cooling in whichrefrigerant normally evaporates in the presence of the inert gascirculating between first and second regions thereof, the improvementwhich comprises flowing liquid refrigerant by gravity between the firstand second regions in the place of cooling and conducting unevaporatedrefrigerant passing from the place of cooling to another place at alower level which is outside the normal path of flow of circulatinginert gas and in which the liquid surface normally is always out ofphysical contact with inert gas when liquid refrigerant is present insaid other place, flowing refrigerant from the other place in a path offlow which includes raising such refrigerant in liquid phase againstgravity by vapor lift action, effecting such raising of refrigerantagainst gravity while out of the presence of the inert gas, andconducting the raised refrigerant back to the place of cooling forgravity flow between the first and second regions thereof.

2. In the art of refrigeration with the aid of an absorptionrefrigeration system in which refrigerant evaporates in the presence ofan inert gas at a place of cooling and absorbed into absorption liquidfrom the inert gas at a place of absorption, the improvement whichcomprises flowing unevaporated refrigerant from the place of cooling toanother place at a lower level out of contact with inert gas andabsorption liquid, vaporizing refrigerant at such other place, flowingthe vaporized refrigerant to a place of condensation, and, while out ofthe presence of the inert gas, conducting condensed refrigerant back tothe place of cooling in a path of flow which includes raising suchcondensed refrigerant by vapor lift action.

3. In the art of refrigeration with the aid of an absorptionrefrigeration system having a circuit for circulation of inert gas andin which refrigerant normally evaporates in the presence of the inertgas at a place of cooling and absorbed into absorption liquid from theinert gas at a place of absorption, the improvement which comprisesflowing unevaporated refrigerant passing from the place of cooling toanother place at a lower level out of contact with inert gas andabsorption liquid, continuously supplying heat to the other place duringoperation of the system to vaporize liquid therein, flowing vaporizedrefrigerant from said other place to a place of condensation, conductingcondensed refrigerant in a path of flow from the place of condensationto the place of cooling,

'l2 and, while out of the presence of the inert gas, raising condensedrefrigerant in such path of flow by vapor lift action.

4. The improvement set forth in claim 3 in which the other place iscontinuously heated by heat dissipated from a place in the system.

5. The improvement set forth in claim 4 in which heat of rectificationis supplied to said other place.

6. In the art of refrigeration employing a system irrcluding a circuitfor circulation of absorption liquid and an evaporator in whichrefrigerant evaporates in the presence of an inert gas, the improvementwhich coniprises adjusting the quantity of refrigerant activelycirculatin'g in the system by withdrawing excess liquid refrigerant fromthe evaporator upon decrease in load, heating such withdrawn liquid at aplace outside the absorption liquid circuit to effect vaporizationthereof, condensing such vaporized refrigerant at a place below theevaporator, and, while out of the presence of the inert gas, raisingsuch condensate to a higher level for recirculation through theevaporator, so as to reeirculate continuously through the evaporatorexcess liquid refrigerant withdrawn therefrom.

7. In an absorption refrigeration system containing an inert gas, acircuit for circulation of such inert gas including an evaporator, acondenser below said evaporator in which refrigerant vapor is liquefied,means for conducting liquid formed in said condenser to said evaporatorincluding a vapor lift tube, a vessel connected to receive excess liquidleaving said evaporator, and means to heat said vessel to vaporizeliquid therein, said condenser bcing connected to receive vapor fromsaid vessel.

8. in an absorption refrigeration system as set forth in claim 7,conduit means including a rectifier for con ducting vapor to saidcondenser, said vessel being arranged to receive heat of rectificationfrom said rectifier.

9. ln an absorption refrigeration system containing an inert gas, acircuit for circulation of such inert gas including an evaporator, acondenser in which refrigerant vapor is condensed and liquefied at alevel below said evaporator, conduit means for conducting liquidrefrigerant formed in said condenser to a part of said evaporator fromwhich such liquid flows therethrough by gravity, said conduit meansincluding a vapor lift tube through which liquid refrigerant is raisedagainst gravity, a vessel in a part of the system which is outside saidinert gas circuit and connected to receive excess liquid leaving saidevaporator, and means for removing such liquid from said vessel to saidconduit means.

l0. ln the art of refrigeration with the aid of an absorptionrefrigeration system in which refrigerant evaporates in the presence ofinert gas at a place of cooling, the improvement which comprises flowingunevaporated refrigerant from the place of cooling to another place at alower level which is out of contact with inert gas and in thermalexchange relation with a place of rectification, and flowing refrigerantfrom said other place at a lower level to said place of cooling,substantially all of such refrigerant reaching said place of coolingfrom said other place in steps which include vaporizing liquid in saidother place by heat of rectification, flowing vaporized refrigerant fromsaid other place to a place of condensation and conducting condensedrefrigerant from the place of condensation to said place of cooling.

ll. In an absorption type refrigeration apparatus having a plurality ofinterconnected parts providing fluid circuits for active circulation ofabsorption liquid, refrigerant fluid and inert gas during normaloperation of the apparatus to produce a refrigerating effect andincluding a condenser connected to receive refrigerant vapor and anevaporator connected to receive liquid refrigerant formed in saidcondenser, a unitary structure which is connected in an active portionof said refrigerant fluid circuit and also provides a pressure vesselhaving the vapor space thereof in communication with said gas circuit,and said refrigerant fluid circuit including connecting means pro vidinga path of flow for gas between said condenser and pressure vessel andfor also conducting to said pressure vessel liquid refrigerant initiallyformed in said condenser.

12. Apparatus as set forth in claim 1l in which said structure alsoembodies provisions for holding a body of liquid in an active portion ofthe absorption liquid circuit.

13. Apparatus as set forth in claim 11 in which said condenser is at alower level than said evaporator and the latter is connected to receiveliquid from said condenser by a vapor lift tube, said structure beingconnected in an active portion of said refrigerant circuit to hold abody of liquid therein which serves as a reaction head for raisingliquid in said vapor lift tube.

14. In absorption type refrigeration apparatus as set forth in claim 11in which said absorption liquid circuit includes a vapor lift pump forcausing circulation of liquid in such circuit and in which saidstructure includes an integral part for holding a body of absorptionliquid which serves as a reaction head under the inuence of whichabsorption liquid is raised by vapor lift action in said pump.

15. Apparatus as set forth in claim 1l in which said structure comprisesa vertically extending tubular member having a partition intermediatethe ends thereof to provide upper and lower chambers, said upper chamberserving as the pressure vessel and the lower chamber being connected inan active portion of said absorption liquid circuit.

16. Apparatus as set forth in claim 11 in which said structure forms ajacket enveloping conduit means forming a part of said gas circuitthrough which relatively cool gas ows from said evaporator, said conduitmeans having an opening in the wall thereof to establish communicationbetween the gas circuit and the interior of said jacket which serves assaid pressure Vessel.

17. Apparatus as set forth in claim 11 in which said structure providingsaid pressure vessel envelops a portion of said gas circuit throughwhich relatively cool gas passes from said evaporator for thermallyshielding said portion to prevent condensation of atmospheric moistureon the outer surfaces thereof.

18. In an air cooled absorption refrigeration apparatus having aplurality of interconnected parts providing a gas which liquidrefrigerant is introduced and an absorber,

and a condenser having an inlet which is connected to receiverefrigerant vapor, pumping means for conducting liquid refrigerant fromsaid condenser upwardly against gravity to the upper part of saidevaporator which is at a higher level than the refrigerant vapor inletof said condenser, structure providing a pressure vessel which isconnected to said condenser and in communication with said gas circuit,said pressure vessel extending vertically downward below the outlet endof said condenser, said condenser comprising a looped coil havingvertically extending portions which are disposed alongside of and spacedfrom one another, and a separate group of fins xed to each of said coilportions to form an air shaft, said pressure vessel being disposedwithin such air shaft.

19. Apparatus as set forth in claim 18 in which said pumping meansincludes a vapor lift tube for normally raising liquid refrigerant byvapor lift action to said evaporator during operation of the apparatus,and said pressure vessel being connected to said condenser and said lifttube to hold a column of liquid therein which serves as a reaction headfor lifting liquid in said lift tube.

20. Apparatus as set forth in claim 18 in which said absorber comprisesa looped coil below said condenser having spaced apart portionssubstantially in vertical alignment with the spaced apart portions ofsaid condenser coil, the portions of the condenser and absorber coilssubstantially in alignment having the same cooling iins fixed thereto.

21. Apparatus as set forth in claim 20 in which said structure providingsaid pressure vessel also provides a vessel in the lower part thereofconnected to receive absorption solution from said absorber coil.

References Cited in the le of this patent UNITED STATES PATENTS2,194,505 Kogel Mar. 26, 1940 2,210,613 Anderson Aug. 6, 1940 2,252,791Ullstrand Aug. 19, 1941 2,264,292 Brace Dec. 2, 1941 2,285,884 Ashbylune 9, 1942 2,295,064 Ullstrand Sept. 8, 1942 2,303,816 Brace Dec. 1,1942 2,401,300 Gross June 4, 1946 2,402,416 Kogel June 18, 19462,468,104 Phillips Apr. 26, 1949 2,490,401 Bergholm Dec. 6, 1949

